Senate Republicans unveiled a revised version of their health care bill on Thursday, and party leaders had planned a vote, or at least to take the procedural steps toward a vote which could have taken place as early as Tuesday.

It was unclear how long the delay will be, reports The New York Times.

“The leader has not announced a date” for the Senate to take up the legislation, said an aide to McConnell.

Meanwhile, two Republican senators — Susan Collins of Maine and Rand Paul of Kentucky — have already said they will not support a motion to proceed to floor debate on the legislation.

A number of other Republicans including Senators Shelley Moore Capito of West Virginia, Dean Heller of Nevada, Lisa Murkowski of Alaska and Rob Portman of Ohio, have also expressed serious reservations about the bill in its current form.